Don't append %interface with ipv6 ips.

- Since netifaces is appending a %interface (i.e: %eth0) at the end and
  does not make a correct ipv6 address we are removing it.
- Improve the tests of whataremyips along the way.

Closes-Bug: 1209443
Change-Id: I585e795083783009961b429607ca3f66b8d7ec30
Merge "Don't append %interface with ipv6 ips."